Issue |
A&A
Volume 463, Number 2, February IV 2007
|
|
---|---|---|
Page(s) | 493 - 502 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20066109 | |
Published online | 23 November 2006 |
The age structure of globular cluster systems in early-type galaxies and its dependence on host galaxy properties*
1
Michigan State University, Department of Physics and Astronomy, 48824 East Lansing, Michigan, USA
2
University of Florida, Department of Astronomy, 211 Bryant Space Science Center, Gainesville 32611, FL, USA e-mail: hempel@astro.ufl.edu
3
European Southern Observatory, Karl-Schwarzschild Str. 2, 85748 Garching, Germany e-mail: mkissler@eso.org
4
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA e-mail: tpuzia@stsci.edu
5
Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany (Founded by merging of the Sternwarte, Radioastronomisches Institut and Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn.) e-mail: mhilker@eso.org
Received:
25
July
2006
Accepted:
13
October
2006
Aims.We present the results of an optical – near-infrared photometric survey of globular cluster systems in early-type galaxies. Our project aims to study correlations between the age structure of the globular cluster systems and environmental as well as structural parameters of their host galaxies.
Methods.To derive the age
structure in globular cluster systems we use combined optical and
near-infrared photometry. This combination facilitates the detection
of young globular cluster sub-populations if their age differs
significantly from the old (~13 Gyr) population, i.e. if their
age is 7 Gyr. We investigate globular cluster systems in
galaxies located in the central regions of galaxy clusters (NGC 1399,
M 87, NGC 4478), galaxies which are members of (sub-) groups (NGC 4365,
NGC 5846) and isolated galaxies (NGC 3115 and NGC 7192). Further, we
look for correlations between globular cluster system properties and
structural parameters of the galaxies (velocity dispersion σ,
color (
), and luminosity MV). For a quantitative
analysis we define the “Methuselah” parameter,
– based on the
fraction of young and old metal-rich globular clusters weighted by age,
characterizing the age structure of a globular cluster system.
Results.We
find that, within our galaxy sample, group galaxies appear to host an
intermediate-age globular cluster population, whereas the globular
cluster systems in cluster galaxies and in rather isolated galaxies
are dominated by an old globular cluster population. A weak
correlation of with the Hβ index of the integrated
light of the host galaxies is the only trend found with respect to
internal galaxy parameters.
Key words: galaxies: star clusters / galaxies: formation / galaxies: evolution / galaxies: fundamental parameters
© ESO, 2007
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